1
GATE ECE 1992
MCQ (Single Correct Answer)
+2
-0.6
The bit stream 01001 is differentially encoded using 'Delay and Ex OR' scheme for DPSK transmission. Assuming the reference bit as a '1' and assigning phases of '0' and '$$\,\pi $$' for 1's and 0's respectively, in the encoded sequence, the transmitted phase sequence becomes
A
$$\,\pi $$ 0$$\,\pi $$ $$\,\pi $$ 0
B
0 $$\,\pi $$ $$\,\pi $$ 0 0
C
0 $$\,\pi $$ $$\,\pi $$ $$\,\pi $$ 0
D
$$\,\pi $$ $$\,\pi $$ 0$$\,\pi $$ $$\,\pi $$
2
GATE ECE 1991
Fill in the Blanks
+2
-0
For the signal constellation shown in the figure, the type of modulation is ________. GATE ECE 1991 Communications - Digital Communication Systems Question 38 English
3
GATE ECE 1990
MCQ (Single Correct Answer)
+2
-0.6
In a BPSK signal detector, the local oscillator has a fixed phase error of 200. This phase error deteriorates the SNR at the output by a factor of
A
$$\cos {20^0}$$
B
$${\cos ^2}{20^0}$$
C
$$\cos {70^0}$$
D
$${\cos ^2}{70^0}$$
4
GATE ECE 1989
MCQ (More than One Correct Answer)
+2
-0
In binary data transmission DPSK is preferred to PSK because
A
a coherent carrier is not required to be generated at the receiver.
B
for a given energy per bit, the probability of error is less.
C
the 1800 phase shifts of the carrier are unimportant.
D
more protection is provided against impulse noise.
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